Composite resin parts may be cured within an autoclave that applies heat and pressure to the part during a cure cycle. Some part geometries include internal cavities that may cause the part to collapse under autoclave pressure unless a tool such as an inflatable bladder is placed in the cavity. Such an inflatable bladder may be inflated during a cure process so as to react the autoclave pressure force applied to the part. Typically, these inflatable bladders are pressurized by venting them to the autoclave pressure through a vacuum bag.
There are several problems with the vented bladders described above that may lead to inconsistencies in the cured parts. For example, failure to properly vent the bladder may prevent the bladder from becoming pressurized sufficiently to react the applied autoclave pressures. Similarly, insufficient bladder pressurization may result from the failure of sealant used to seal a vent hole coupling the bladder with an outside vent. It is also possible for a bladder wall to fail or be penetrated, in which event autoclave gases may be forced into the part throughout the cure cycle. Accordingly, there is a need for a bladder system that may reduce or eliminate the adverse effects resulting from leaks in the bladder or failure to properly pressurize the bladder. There is also a need for a bladder system and curing method that utilizes venting the bladder system to an external pressure, such as an autoclave pressure, while at the same time also eliminating the need for vacuum bag vent hole seals.